1. Field of the Invention
The present invention generally relates to a planetary gear train, a wind turbine generator and a manufacture method of a carrier of the planetary gear train, and in particular, to an oiling mechanism for oiling a bearing of a planetary gear in a planetary gear train.
2. Description of the Related Art
A planetary gear train is one of mechanisms widely used as step-up gear boxes and reduction gear boxes. A planetary gear train has an advantage that a large reduction ratio can be obtained with a small number of gears and a large torque can be transferred. Such an advantage is preferable for a wind turbine generator and the planetary gear train is widely employed as the step-up gear box of the wind turbine generator.
One of technical matters to be taken into consideration in using a bearing as a bearing of a planetary gear in a planetary gear train is supply of lubricant oil to the bearing. In order to prolong a lifetime of a bearing, it is desirable to perform forcible oiling. Feeding lubricant oil by forcible oiling allows keeping the performance of the oil film, prolonging the lifetime of the bearing. One problem is that the bearing of a planetary gear in a planetary gear train is provided on a rotating body (i.e., a carrier). Forcible oiling to the bearing of a planetary gear in a planetary gear train requires supplying lubricant oil from a stationary body (e.g., a housing) to the bearing provided on the rotating body. Here, an improper design of a lubricant oiling supply system for supplying lubricant oil from the stationary body to the bearing on the rotating body causes leakage of the lubricant oil, which is undesirable in operating a wind turbine generator. Although use of a complicated seal structure may prevent the leakage of lubricant oil, this increases the cost on the contrary. Japanese Patent Application Publication No. P2007-333141A discloses a widely used seal structure between a stationary body and a rotating body, for example. Also, Japanese Patent Application Publication No. P2009-243570A discloses a seal structure adapted to a power transmission device, for example.